#include <stdio.h>
#include <string.h>

#define M 1046527
#define NIL (-1)
#define L 14
char H[M][L];
int getChar(char ch) {
    if (ch == 'A') return 1;
    else if (ch == 'C') return 2;
    else if (ch == 'G') return 3;
    else if (ch == 'T') return 4;
    else return 0;
}
long long getKey(char str[]) {
    long long sum = 0, p = 1, i;
    for (i = 0; i <strlen(str); ++i) {
        sum += p * (getChar(str[i]));
        p *= 5;
    }
    return sum;
}
int h1(int key) {return key % M;}
int h2(int key) {return 1 + (key % (M - 1));}

int find(char str[]) {
    long long key, i, h;
    key = getKey(str);
    for (i = 0; ; ++i) {
        h = (h1(key) + i * h2(key)) % M;
        if (strcmp(H[h], str) == 0) return 1;
        else if (strlen(H[h]) == 0) return 0;
    }
}

int insert(char str[]) {
    long long key, i, h;
    key = getKey(str);
    for (i = 0; ; ++i) {
        h = (h1(key) + i * h2(key)) % M;
        if (strcmp(H[h], str) == 0) return 1;
        else if (strlen(H[h]) == 0) {
            strcpy(H[h], str);
            return 0;
        }
    }
}
int main() {
    int i, n, h;

    char str[L], com[9];
    for (i = 0; i < M; ++i) H[i][0] = '\0';
    scanf("%d", &n);
    for (i = 0; i < n; ++i) {
        scanf("%s %s", com, str);
        if (com[0] == 'i') insert(str);
        else {
            if (find(str))
                printf("yes\n");
            else
                printf("no\n");
            
        }
    }
}